In the 3rd Generation Partnership Project (3GPP), a radio access method and a radio network for cellular mobile communications (hereinafter referred to as “Long Term Evolution (LTE)”, or “Evolved Universal Terrestrial Radio Access (EUTRA)”) have been discussed. In LTE, a base station device is also referred to as an evolved NodeB (eNodeB), and a terminal device is also referred to as user equipment (UE). LTE is a cellular communication system in which an area is divided into a plurality of cells to form a cellular pattern, each of the cells being served by a base station device. A single base station device may manage a plurality of cells.
LTE supports a time division duplex (TDD). LTE that employs a TDD scheme is also referred to as TD-LTE or LTE TDD. In TDD, an uplink signal and a downlink signal are multiplexed in time division. Furthermore, LTE supports a frequency division duplex (FDD).
In the 3GPP, a carrier aggregation has been specified where a terminal device is capable of simultaneously performing transmission and/or reception in up to five serving cells (component carriers).
In the 3GPP, simultaneous transmission and/or reception by a terminal device in over five serving cells (component carriers) has been considered (NPL 1). Furthermore, a terminal device that transmits a physical uplink control channel in a secondary cell that is a serving cell other than a primary cell has also been considered (NPL 1).